Planet rang like a bell, sand danced to seismic waves

California's largest earthquake in four years caused earth to ring "like a bell" and mountains to grow taller, geologists said.

Earthquakes relieve pressure between clashing continental plates. The plates float on the earth's mantle, which has a putty-like consistency and moves as the earth's core heats it.

On Monday, one piece of crust shoved beneath another about 7.6 kilometres beneath the surface of the earth and at the intersection of the Pacific and North American plates, US Geological Survey seismologists said.

That sent tremors along America's west coast and beyond. "For an earthquake this size, every single sand grain on the planet dances to the music of those seismic waves," geological survey spokesman Ross Stein said. "You may not be able to feel them, but the entire planet is rung like a bell."

The earthquake struck on what is believed to be the San Simeon thrust fault. Pressure in a thrust fault is relieved when one piece of earth pushes up on top of another, compared with lateral faults, such as the San Andreas, in which two piece of crust slide next to one another. Thrust faults produce mountains and the San Simeon quake probably improved the view from nearby hills, Mr Stein said because "mountains have probably been pushed up about a foot or so by this earthquake".